Process of obtaining pyrobetulin.



0. 65|,942. Patented lune I9, I900. J. WHEELER. PROCESS OF MAKING PYROBETULIN.

. (Applicaltion filed Dec. 30 1391. (No'modeL) 3 Sheets-Sheet I.

/"[21 eases Inventor.

Ma ,nomzxs PETERS ca. mom-um. wunme-rou. D. c.

No. 65!,942. Patented lune l9, I900. J. WHEELER.

PFIOIJESSDF MAKING PYROBETULIN.

(App1ica.tion filed Dec. 30, 1897.) (No Model.) -3 Sheots'Sheet 2.

' UNITED 5mm J PATENT OFFICE.

JAMES WHEELER, or ILFRAOOMBE, ENGLAND.

P OCESS OF OBTAINING PYROBETU LIN.

emomicmon formingpart of Letters Patent No. 651,942, dated Tune 19, 1900.

'Original application filed Tune 16, 1897, Serial No. 641,041. Divided and this application filed December 80, 1897. Serial No. l

' 664,758. (Nd specimens.)

To all whom, it may concern/,

Be it known that I, JAMES WHEELER, a subject of the Queen of Great Britain and Ireland, residing at Ilfracombe, in' the county of Devon, England, have invented an Improvement in the Manufacture or Production of Pyrobetulin or Pyrobetulin Anhydrids, of which the following is a specification.

In the specification of other Letters Patent granted to me, dated September 20, 1898, and numbered 611,047, I have described and claimed a method and apparatus for producing films. Now this application, which is a division of the said application, relates to the manufacture or production from birch-bark or the like of certain substances hereinafter called pyrobetulin or pyrobetulin anhydride -i. e., betulin (0 E 0 or betulin anhydride (C H O (m'de Watts Chemistry, 1888 edition) or products analogous thereto, obtained by burning and consequent dry distillation. According thereto pyrobetulin or pyrobetulin anhydride is producedby burning in a closed chamber without flame and in a current of air material containing betulin to an amount bearing a suitable ratio to the capacity of the said chamber. In order to obtain pyrobetulin, the material is burned with an abundant air supply, whereas to obtain pyrobetulin anhydride the material is I burned with a restricted air-supply, with the result that in the former case there is burned away the cortical investment of the betulin of the bark and in the latter case the pyrobetulin thus produced is converted into its anhydride by the more prolonged heating an d slower evolution of the fumes;

In carrying my invention into practical effeet I may employ the combustible material in the form of tablets or small blocks, (hereinafter called tablets,) made by compress ing together a mixture comprising finelyground epidermis of birch-bark, preferably that of white birch or hetirlaj 'alba, and an oxygen-carrier, such as nitrate of potassium. The percentage of nitrate of potassium in the material may vary. For the production of pyrobetulin the-percentage may vary from four to eight, and for producing pyrobetulin anhydride it may vary from one to four. When less than two per cent. of nitrate of potassium is used, the materialshould be dried for a considerable time both before and after compression. In the case of high percentages of nitrate of potassium it is advisable, in order to lessenthe tendency of the charge (when burning) to burst into flame, to dissolve the nitrate of potassium either in plain water or in a weak solution of dextrin, so as, for example, to give one per cent. of dextrin to the ainountof bark used. In order to produce pyrobetulin, the tablets are arranged so as to give a space around each to allow of the free passage of an ample supply of air, whereas to produce pyrobetulin anhydride the tablets are placed near together, so as to insure a restricted passage of air, whereby a slower combustion will be attained than with the former arrangement.

Figures 1 and 2 of the accompanying drawings are sectional views taken at right angles to each other of an apparatus. suitable for producing pyrobetulin or pyrobetulin anhydride according to this invention. Fig. 3 is a partial plan representing a support for a lamp. Fig. 4 shows the lamp half in vertical section and half in elevation. Figs. 5, 6, and 7 are respectively a plan of a chargeplate, an elevation of an annular distancepiece, and a plan of a floor-plate used in producing pyrobetulin; and Figs. 8 and 9 are respectively plans of a charge-plate and a floorplate used in producing pyrobetulin anhydride. Figs. 4 to 9, inclusive, are drawn to a larger scale than the other figures.

The apparatus shown comprises a chamber 1, of sheet-zinc, which has in its top an opening 2, preferably of circular shape, through which it communicates with an upper compartment 3, formed by a conical cover 4, that fits upon the top of the chamber 1, forming therewith around the opening 2 an air-tight joint by means of an india-rubber ring 5 and a flange 6 or other suitable means; The bottom of the chamber 1 may be closed in a sufficiently air-tight manner by placing it upon a thick cloth or other compressible material. At the center of the opening 2 there is supported from the top of the chamber 1, by means of bars 7, (see Fig. 3,) soldered or otherwise secured thereto, a suitable stand8 for a lamp in which to burn the tablets.

This lamp may, as shown, comprise a .cylin-' drical cup 9, (see Fig. 4,) perforated, as shown, at its lower part to admit air and adapted in its upper part to support, by means of brackets 10, a floor-plate 11, on which is placed 'a ring or distance-piece 12, (see also Fi'g. 6,) which supports a charge-plate 13, in which the tablets are arran ged with their lower edges resting more or less onthe floor-plate 11. The lower portion of the cup 9 may be surrounded by a ring (not shown) having apertures in itcorresponding to the perforations in the cup, so that by slightly turning the ring on the cup the supply of air passing through the perforations of the cup may be accurately adjusted. I

Toproduce pyrobetulin, the floor-plate may advantageously consist, as shown in Fig. 7,

of two concentric rings 14 and 15, of metal,

connected by radial pieces 16, of metal, and

the charge-plate 13 may, as shown in Fig. 5,

' be. a plate of metal'having a numberof radial openings 17 made through it for the due retention of the tablets,with an air-space around each, (17 are air-holes,) other openings, some radial and between adjacent ones of the aforesaid radial openings and some near the center of the plate, being made through the plate. vfor the passage of air therethrough. lhe edges of the tablets will then rest more or less on the inner ring. For a larger lamp the floor-plate may have two or more concentric inner rings and the charge-platea. corresponding number of concentric rings of tablet-containing holes (of any desired capacity, accordingto the size of the tablets employed) with intervening air-holes.

.F'or producing pyrobetulin anhydride the,

floor plate may advantageously consist, as shownv in Fig. 9., of a metal ring 18, having opposite sides connected together by a number of .parallel ban-s19, and the charge-plate may consist, as shown in Fig. 8, of a similar ring 20, having two intersecting sets of bars 21 and 22, respectively, that connect opposite sides, but are placed at'acomparatively-great distance apart, and between which the tablets are arranged near together transversely tothe-bars '19 of thefloor-plate;

The tablet-containing holes or spaces of the charge-plates, whether for producing pyrobetnlin or for producing pyrobetulin anhydride, may be made with sinuous outlines or otherwise, so as to prevent the checking of the extrication of the fumes that might otherwise'occur through the swelling of the tablets, especially in the case of large tablets.

-The lamp is provided with a chimney 23, of'

the lamp, as hereinbefore-described, are ig-' nited simultaneously by means of ajet or jets of gas caused to play upon their upper "its proper handling, whenarranged for producing pyrobetulin anhydride, in order more completely to prevent at the outset the evolution of low-temperature fumes adapted to produce pyrobetulin- 36 and 37 are apertures provided at oppo-' eight inches, while the opening inits top was nine inches in diameter, the heightof the cover twelve inches, and the diameter of the cup of the lamp two and one-fourth inches, this being adapted for small circular'tablets of about five-eighths of an inch in diameter.

With this apparatus 1 haveem'ployed tablets to the full extent of the respective chargeplates. The cover here described would be large enough for a chamber very considerably larger than the one here referred to.

In the case of a chamber 1- of". very large area a hook or ring at each. corner and connected with a common rope or chain passing over an overhead pulley is convenient for raising the chamber to allow of the removal of the deposited material from the floor of the chamber. Furthermore, the conical cover may be made in two parts formin gan air-tight joint with each other by mean-s of flanges, the lower part supporting the stand for the lamp and having either one or more internal annulargrooved depressions or channels or-correspondin g projections adapted to prevent condensed moisture from running down and fallpyrobetulin or pyroin-g upon the deposited betulin anhydride.

For reducing. the epidermis of birch-bark to a su-fiicie-ntlyfine powder to produce thecombustible material or tablets I first pass it through a disintegrator until it is reduced to a finely-shredded condition. I then dry it by exposing it to the air freely and to a temperature of 150 Fahrenheit during three days, and I then pass itrepeatedly under heavy stone edge runners until sufiiciently fine to pass through a sieve having sixty holes to the linear inch.

When material containing betulin is burned under the conditions hereinbefore described, the cortical investment (in the case of birchbark) or other matter surrounding or inclosing the betulin becomes by contact with the burning zone heated to such an extent that aided by the current of air produced by the heat of combustion it volatilizes the betulin. When the tablets are arranged in close contact, so as to give a limited air-supply, the temperature of combustion and relativelylong heating are such as to eliminate more or less completely a molecule of water, and thus to produce pyrobetulin anhydride; but when the tablets are so arranged as each to have an abundant air-supply the temperature of combustion is too low and the evolution of the fumes too rapid to effect this elimination, with the result that pyrobetulin itself is deposited in the chamber 1.

What I claim is- 1. The hereinbefore-described process, consisting in burning, without flame, by the unaided heat of its own combustion, and in a chamber of suitable size closed to the outer air, a mixture containing betulin and an oxygen-carrier.

2. Process of obtaining pyrobetulin or pyrobetulin anhydride by compressing together into blocks or tablets a mixture comprising or containing finely-ground epidermis or outer rind of birch-bark and an oxygen-carrier such as nitrate of potassium, and burning in a closed chamber without flame, a quantity of the said blocks or tablets bearing a suitable proportion to the air capacity of the said chamber, substantially as hereinbefore de= scribed.

3. Process of obtaining pyrobetulin or pyrobetulin anhydride by compressing together into blocks or tablets a mixture comprising or containing finely-ground epidermis or outer rind of birchbark and an oxygen-carrier such as nitrate of potassium, arranging in aclosecl chamber a quantity of the said blocks or tablets bearing a suitable proportion to the air capacity of the said chamber in such a manner that when ignited they will all have either an abundant or a limited supply of air, and burning the said blocks or tablets in the said chamber without flame, substantially as hereinbefore described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JAMES WHEELER.

Witnesses:

W. O. HUTCHINGS, S. ROTTENBURG. 

